1. Field of the Invention
The present invention relates to a method of manufacturing a current collector of a flow board of a fuel cell. The flow board has high methanol resistance, high mechanical strength, superior fuel flow efficiency, and low cost.
2. Description of the Prior Art
A fuel cell is an electrochemical cell in which a free energy change resulting from a fuel oxidation reaction is converted into electrical energy. Fuel cells utilizing methanol as fuel are typically named as Direct Methanol Fuel cells (DMFCs), which generate electricity by combining gaseous or aqueous methanol with air. DMFC technology has become widely accepted as a viable fuel cell technology that offers itself to many application fields such as electronic apparatuses, vehicles, military equipments, aerospace industry and so on.
DMFCs, like ordinary batteries, provide dc electricity from two electrochemical reactions. These reactions occur at electrodes (or poles) to which reactants are continuously fed. The negative electrode (anode) is maintained by supplying methanol, whereas the positive electrode (cathode) is maintained by the supply of air. When providing current, methanol is electrochemically oxidized at the anode electrocatalyst to produce electrons, which travel through the external circuit to the cathode electrocatalyst where they are consumed together with oxygen in a reduction reaction. The circuit is maintained within the cell by the conduction of protons in the electrolyte. One molecule of methanol (CH3OH) and one molecule of water (H2O) together store six atoms of hydrogen. When fed as a mixture into a DMFC, they react to generate one molecule of CO2, 6 protons (H+), and 6 electrons to generate a flow of electric current. The protons and electrons generated by methanol and water react with oxygen to generate water. The methanol-water mixture provides an easy means of storing and transporting hydrogen, much better than storing liquid or gaseous hydrogen in storage tanks.
The DMFC module usually includes a current collector (or also referred to as charge collector board) and a flow board, which both play important roles. The current collector collects the electrons generated from the electron-chemical reaction, and the flow board manages and controls the distribution of the fuel. In the past, the flow board design has focused on enabling fuel to pass smoothly through the fuel channel into the membrane electrode assembly (MEA).
The prior flow boards use graphite or glass fiberboard such as FR4, FR5 as the materials of the body substrates. Conventionally, the flow board is made using a computer numerical control (CNC) mill lathe. The shortcomings of CNC mill lathe include low yield and high cost. The prior body substrates, which are made of graphite, FR4, or FR5, have poor mechanical properties, and occupy too much space. The above reasons are disadvantageous for the yield and popularization of the fuel cell.
To apply the fuel cell in the laptops, cellular phones or PDA, reduction both in cost and cell volume are required. Hitherto, there are still challenges in developing relevant elements of fuel cells. There is a strong need in this industry to combine these relevant elements with fuel cell mechanism at design phase thereby obtaining breakthrough in aspects of lighter, thinner, smaller fuel cell devices or modules, which are more practicable.
In conclusion, a well designed flow board does not only depend on choosing a material that is resistive to corrosion caused by gaseous/liquid fuel and/or the chemical reactant, but also requires choosing a material that has superior mechanical properties, low cost, and fast mass production. There is a need to improve both the materials and the manufacturing methods utilized in conventional flow boards.